Merge branch 'feature/rtc_clk_impl' into 'master'

Introduce soc component, add source of rtc_clk and rtc_pm libraries

This MR adds parts of the RTC library source code (initialization, clock selection functions, sleep functions). WiFi-related power management functions are kept inside the precompiled library. Most of RTC library APIs have been renamed.

Default CPU frequency option in Kconfig is set to 160MHz, pending qualification of 240MHz mode at high temperatures.

Register header files are moved into the new soc component, which will contain chip-specific header files and low-level non-RTOS-aware APIs (such as rtc_ APIs). Some of the files from ESP32 component were also moved: cpu_util.c, brownout.c, and the corresponding header files. Further refactoring of ESP32 component into more meaningful layers (chip-specific low level functions; chip-specific RTOS aware functions; framework-specific RTOS-related functions) will be done in future MRs.

See merge request !633

components/bootloader/src/main/bootloader_start.c

@@ -29,6 +29,7 @@
 
 #include "soc/soc.h"
 #include "soc/cpu.h"
+#include "soc/rtc.h"
 #include "soc/dport_reg.h"
 #include "soc/io_mux_reg.h"
 #include "soc/efuse_reg.h"
@@ -45,7 +46,7 @@
 #include "bootloader_flash.h"
 #include "bootloader_random.h"
 #include "bootloader_config.h"
-#include "rtc.h"
+
 #include "flash_qio_mode.h"
 
 extern int _bss_start;
@@ -234,12 +235,13 @@ static bool ota_select_valid(const esp_ota_select_entry_t *s)
 
 void bootloader_main()
 {
-    /* Set CPU to 80MHz.
-       Start by ensuring it is set to XTAL, as PLL must be off first
-       (may still be on due to soft reset.)
-    */
-    rtc_set_cpu_freq(CPU_XTAL);
-    rtc_set_cpu_freq(CPU_80M);
+    /* Set CPU to 80MHz. Keep other clocks unmodified. */
+    uart_tx_wait_idle(0);
+    rtc_clk_config_t clk_cfg = RTC_CLK_CONFIG_DEFAULT();
+    clk_cfg.cpu_freq = RTC_CPU_FREQ_80M;
+    clk_cfg.slow_freq = rtc_clk_slow_freq_get();
+    clk_cfg.fast_freq = rtc_clk_fast_freq_get();
+    rtc_clk_init(clk_cfg);
 
     uart_console_configure();
     ESP_LOGI(TAG, "ESP-IDF %s 2nd stage bootloader", IDF_VER);
@@ -722,16 +724,7 @@ static void uart_console_configure(void)
 
     // Set configured UART console baud rate
     const int uart_baud = CONFIG_CONSOLE_UART_BAUDRATE;
-    uart_div_modify(uart_num, (APB_CLK_FREQ << 4) / uart_baud);
+    uart_div_modify(uart_num, (rtc_clk_apb_freq_get() << 4) / uart_baud);
 
 #endif // CONFIG_CONSOLE_UART_NONE
 }
-
-/* empty rtc_printf implementation, to work with librtc
-   linking. Can be removed once -lrtc is removed from bootloader's
-   main component.mk.
-*/
-int rtc_printf(void)
-{
-    return 0;
-}